All eight of Keele’s patents are here, as of Feb. 2012.
Patents [1 - 3] cover my constant-directivity (CD) horns. Patent  covers the EV “White Horns” that that were the first constant-directivity (CD) horns: models HR9040, HR6040, and HR4020. Patents [2 - 3] cover the later JBL CD horns: models 2344, 2360, 2365, 2366, 2370, 2380, 2404, and the “Defined-Coverage” speaker system model 4660.
Patent  covers an interesting digital FIR filter scheme where the taps are spaced logarithmically in time rather than linearly in time. This automatically generates a filter that has a frequency response with log-spaced features and covers a wide frequency range with very few taps.
Patents [6 - 7] specifically deal with CBT arrays.
 D. B. Keele, Jr., “Horn Loudspeaker,” U. S. Patent No. 4,071,112 (Jan. 1978).
A loudspeaker with a driver and horn in which the horn has a channel expanding in cross section exponentially from the throat of the horn to a second portion, the second portion expanding conically to a rapidly flaring bell portion which terminates in the mouth of the horn. In one embodiment, the channel has a rectangular cross section to provide a wider horizontal beam width than vertical beam width.
 D. B. Keele, Jr., “Loudspeaker Horn,” U. S. Patent No. 4,308,932 (Jan. 1982).
A loudspeaker horn having improving directivity has a pair of smoothly flared vertical sidewalls joined to a pair of smoothly flared horizontal sidewalls. In an exemplary embodiment, one pair of sidewalls is generated as a surface of revolution, with the curvature of the surface being defined by a power series formula. The contour of the remaining pair of sidewalls is also defined by the power series formula, although different constants may be used. The vertical and horizontal sidewalls are separately defined and are substantially congruent at the rectangular or square mouth. In the exemplary embodiment, the gap formed at the back of one of the pairs of sidewalls is connected to the throat formed at the back of the other pair of sidewalls by a connecting section having an arcuate area which monotonically increases from the throat to the gap.
 D. B. Keele, Jr., “Defined Coverage Loudspeaker Horn,” U. S. Patent No. 4,580,655 (Apr. 1986).
Opposed side walls of a loudspeaker horn are constructed to direct portions of a sound beam toward a target over different preselected included angles, producing an incident beam which is substantially coextensive with the target. The side walls preferably extend downstream at the preselected angles over a distance at least comparable to a maximum wavelength at which the horn is to be used.
 Steven W Hutt, John F Steere, D. B Keele, Jr., “Acoustic Lens System,” U. S. Patent No. 7,316,290 (Jan. 2008).
A loudspeaker includes a frame, a magnet coupled to the frame and a diaphragm secured to the frame. An acoustic lens may be positioned in front of the diaphragm. An aperture extends through the acoustic lens. The acoustical directivity pattern of the loudspeaker may be modified by the acoustic lens to improve the uniformity of the off axis vs. on axis sound pressure level.
 D. B Keele, Jr., “Log-Sampled Filter System,” U. S. Patent No. 7,555,081 (Jan. 2009).
This invention provides a filter system which may be implemented with less hardware and software resources than traditional filters. In addition, the filter system structure reduces the complexities typically associated with filter design by permitting direct specification of the filter frequency response. Thus, the filter system may adaptively change the filter frequency response on the fly without incurring excessive time or computational costs. The filter system may provide a filtered signal output to any subsequent processing system, such as a voice recognition system or audio reproduction system.
 D. B Keele, Jr., “Reflective Loudspeaker Array,” U. S. Patent No. 7,684,574 (Mar. 2010).
A reflective loudspeaker array is cooperatively operable with an acoustically reflective planar surface to provide a constructive combination of direct and reflected sound waves that produces a uniform sound field. The uniform sound field provides a controlled sound field in the vertical and horizontal direction, and also provides uniformity from distances close to the reflective loudspeaker array to far way. The direct and reflected sound waves are advantageously and constructively combinable to generate a focused beamwidth of soundwaves. The reflective loudspeaker array includes a plurality of loudspeakers coupled to a surface of the reflective loudspeaker array. The surface may be formed to include at least one curve with a radius of curvature. The reflective loudspeaker array may be placed adjacent an acoustically reflective planar surface such that a frontal plane of a loudspeaker adjacently located closest to the acoustically reflective planar surface is aligned perpendicularly, and a frontal plane of a loudspeaker spaced away from the acoustically reflective planar surface is not aligned perpendicularly.
 D. B Keele, Jr., “Constant-Beamwidth Loudspeaker array,” U. S. Patent No. 7,826,622 (Nov. 2010).
A loudspeaker is provided for receiving an incoming electrical signal and transmitting an acoustical signal that is directional and has a substantially constant beamwidth over a wide frequency range. The loudspeaker may include a curved mounting plate that has curvature over a range of angles. The loudspeaker may include an array of speaker drivers coupled to the mounting plate. Each speaker driver may be driven by an electrical signal having a respective amplitude that is a function of the speaker driver's respective location on the mounting plate. The function may be a Legendre function. Alternatively, the loudspeaker may include a flat mounting plate. In this case, the respective electrical signal driving each speaker may have a phase delay that virtually positions the speaker onto a curved surface.
 Steven W. Hutt, D. B. Keele, Jr., “Vehicle Loudspeaker Array,” U. S. Patent No. 8,073,156 (Dec. 2011).
An audio processing system for a vehicle includes a plurality of loudspeakers positioned to form a single line array. The loudspeaker line array is positionable in a vehicle on a dashboard of the vehicle substantially at the convergence of the dashboard and a window of the vehicle. When the loudspeaker line array is driven by an audio signal, a vertically and horizontally focused and narrowed sound pattern is perceived by a listener in the vehicle. The sound pattern is the result of the constructive combination of the direct sound impulses and the reflected sound impulses produced by each loudspeaker in the array. Using delay, attenuation and phase adjustment of the audio signal, the sound pattern may be controlled, limited, and directed to one or more locations in the vehicle.